2019-09-15T11:44:11Zhttps://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/227092018-09-14T07:35:53Zcom_10261_63com_10261_6com_10261_42343com_10261_2col_10261_316col_10261_4234400925njm 22002777a 4500dcToral, Pablo G.authorFrutos, PilarauthorHervás, GonzaloauthorGómez-Cortés, PilarauthorJuárez, ManuelaauthorFuente, Miguel Ángel de laauthor2010-04Ruminant diet supplementation with sunflower oil (SO) and fish oil (FO) has been
reported as a good strategy for enhancing some milk fat compounds, such as conjugated
linoleic acid (CLA) and omega-3 polyunsaturated fatty acids (PUFA) in dairy cows, but
no information is available regarding dairy sheep. In this work, ewe diet was
supplemented with FO, alone or in combination with SO, with the aim of improving
milk nutritional value and evaluating its effect on animal performance. Sixty-four Assaf
ewes in mid-lactation, fed a high-concentrate diet, were distributed in 8 lots of 8 animals
each and assigned to 4 treatments (2 lots per treatment): no-lipid supplementation
(Control), or supplementation with 20 g SO/kg (SO), 10 g FO/kg (FO), or 20 g SO plus
10 g FO/kg (SOFO). Milk production and composition, including a complete fatty acid
profile, were analysed on days 0, 3, 7, 14, 21, and 28 on treatments. FO supplementation
tended to reduce DM intake in comparison with the Control treatment (-15%), and its
use in combination with SO (SOFO) resulted in a significant decrease in milk yield as
well (-13%). All lipid supplements reduced milk protein content, and FO also reduced
milk fat content, by up to 21% alone (FO) and 27% in combination with SO (SOFO).
Although the mechanisms involved in FO-induced milk fat depression are not wellestablished
yet, the observed increase in some milk trans-FA that are putative inhibitors
of milk fat synthesis, such as trans-9 cis-11 CLA, and the almost 3-fold decrease in
C18:0 (consistent with the theory of reduced milk fat fluidity) may be involved. When
compared with the Control, lipid supplementation remarkably improved the milk
content of rumenic acid (cis-9 trans-11 CLA; up to 4-fold increases with SO and SOFO
diets), whereas FO-containing diets also increased milk omega-3 PUFA, mainly
docosahexanoic acid (DHA, with mean contents of 0.29 and 0.38% of total fatty acids
for SOFO and FO, respectively), and reduced the omega-6/omega-3 FA ratio to approximately half the control value. All lipid supplements resulted in high levels of
some trans-FA, mainly trans-11 C18:1 (vaccenic acid) but also trans-10 C18:1.Journal of Dairy Science 93(4): 1604-1615 (2010)0022-0302http://hdl.handle.net/10261/2270910.3168/jds.2009-2530Changes in milk fatty acid profile and animal performance in response to fish oil supplementation, alone or in combination with sunflower oil, in dairy ewes